Hayate no Gotoku! Episode 9, title name as Eloim Essaim. Mr. Cow, Mr. Cow! What is it, Mr. Frog? (エロイムエッサイム.ウシくんウシくん!なんだいカエルくん?) ,Eroimu Essaimu. Ushi-kun Ushi-kun! Nandai Kaeru-kun??) aired on May 27th 2007, the English Animax dub aired on June 23rd 2009.
When Isumi was about to leave, Nagi said that if they separate now, they won't be able to see each other again, in which Isumi told Nagi that she should have gone go school once again. The following day, Hayate woke Nagi up and takes her to Hakuo Academy, even though she doesn't want to. Tama asked Hayate that does he have a school to go, and Hayate responded that he can't go to school since he is working for Nagi in 40 years. Meanwhile, Isumi grabbed Nagi and warned her that she should not go to an old suspicious building school.
After Hayate took Nagi home, Nagi realizes that she forgot her notebook and left it at school. Hayate went back to Hakuou Academy to pick up Nagi's notebook, only to be stopped by Yukiji who appeared out of nowhere. Hayate asked Yukiji to let him borrow her classroom keys in order to retrieve Nagi's notebook, so they went inside the Academy and saw inside Yukiji's room, which is a mess. Just then, Miki, Izumi, and Risa appeared and asked Hayate about what is he doing there. The three girls turns out to be Yukiji's students and Yukiji let Hayate borrow her classroom keys and tells him to bring it back. Yukiji and the three girls warned Hayate that the old building school that he is suppose to go is actually a haunted old building school, where the evil ghost spirits live there at night.
As Hayate entered the haunted building school, Nagi called Hayate and tells him that she is worried about him not coming back. After Nagi hangs up, Hayate fell from that old cracked floor inside the haunted building school. Meanwhile, Yukiji and the trio are wondering about what will happen to Hayate, as Hinagiku came by and they told her that Hayate got lost in the haunted house, so Hinagiku went to look for him. Back in the haunted house, Hinagiku realizes that she is scared of a ghost and she screamed in horror. Hayate heard Hinagiku scream as she was being chased by a haunted doll, until Hayate saves her by destroying that doll. After that, Hayate told Hinagiku that they should leave, but Hinagiku said that she will not leave until she defeats the mastermind behind that haunted house, so Hayate follows her. While Hayate wonders if Hinagiku is as stubborn as Nagi, the doll, whom they thought it was destroyed, came back, and Hinagiku starts fighting it. After the fight, the doll exploded, and the two of them moves on to find Nagi's notebook. While Isumi and her butlers went to destroy the real evil spirit, Hayate came back to Nagi safely with her notebook, and wonders about a school being a nice place.